Conventionally, there has been known a laser printer including a photosensitive drum on which an electrostatic latent image is formed, a developing roller that transforms the electrostatic latent image into a visible image, and a toner box that accommodates a toner to be supplied onto the developing roller.
As such laser printer, there has been proposed, for example, an image forming apparatus including a photosensitive member, and an image forming unit that is provided around the photosensitive member and sequentially performs respective steps of charging, exposure, and development along with rotation of the photosensitive member.
In the image forming apparatus, a toner cartridge that replenishes a toner to a developing device configuring an image forming unit is replaceably mounted to a casing that accommodates a magnet roller in the developing device. The toner cartridge is arranged in opposed relation to the developing device in a longitudinal direction of the magnet roller in a state of being mounted in the casing. In the state where the toner cartridge is mounted in the casing, a replenishing port formed in the toner cartridge and a supply port formed in the casing are communicated with each other, and a toner is replenished from the toner cartridge to the developing device through the replenishing port and the supply port. Further, during replacement of the toner cartridge, a front cover of an image forming apparatus body is opened, and the toner cartridge is then attached and detached to and from the casing along the longitudinal direction described above.
Further, in such a laser printer, a toner box that is detachably mountable to the laser printer body has been proposed, and a mechanism to prevent toner leakage during attachment and detachment of the toner box has also been proposed together therewith.
For example, there has been proposed a toner replenishing device in which a cover provided in a main body case incorporating a copying mechanism is opened to attach and detach a toner cartridge to and from a toner container provided in the main body case.
In the toner replenishing device, a toner cartridge insertion portion and a toner storage section is provided in the toner container, and further, a shutter member is provided openably/closably between the toner cartridge insertion portion and the toner storage section. The shutter member is engaged with an engaging portion provided in the toner cartridge, and is moved to a closed position when the toner cartridge is moved to an attachment/detachment position. This seals the toner storage section with the shutter member, so that toner leakage from the toner storage section (on the body casing side) can be prevented during attachment/detachment of the toner cartridge.
Further, there has been proposed a color electrophotographic printer including a photosensitive member, and a plurality of developers for developing an electrostatic latent image formed on the photosensitive member.
In the color electrophotographic printer, a toner cartridge is detachably mounted in a developing housing of each developer, and a toner is supplied from a toner discharge port of the toner cartridge to a toner supply port in the developing housing. A cartridge-side shutter for opening/closing the toner discharge port, and a developer-side shutter for opening/closing the toner supply port are provided in the toner cartridge and the developing housing, respectively. The cartridge-side shutter is engaged with a shutter engaging piece formed on the developing housing, and the developer-side shutter is engaged with a shutter engaging piece formed on the toner cartridge. Therefore, when the toner cartridge is pivoted, the cartridge-side shutter and the developer-side shutter are opened/closed together, so that the toner discharge port and the toner supply port are opened/closed. Thus, during attachment/detachment of the toner cartridge, the toner discharge port and the toner supply port are closed by closing the cartridge-side shutter and the developer-side shutter, thereby preventing toner leakage from the toner cartridge and the developer (on the color electrophotographic printer body side).
Further, there has been proposed a laser printer in which a photosensitive member is provided in an apparatus body, a developer is arranged around the photosensitive member, and an electrostatic latent image formed on a surface of the photosensitive member is transformed into a visible image.
In the laser printer, a toner cartridge is detachably mounted to the developer, and a toner is supplied from the toner cartridge to the developer through an opening provided in the toner cartridge and a replenishing port provided in a developing chamber of the developer. The toner cartridge has a shutter for opening/closing the opening, and the shutter is opened/closed by opening/closing an upper structure, which is a cover of an apparatus body, after the toner cartridge is attached to the developer. Thus, during attachment/detachment of the toner cartridge, the opening is closed by closing the shutter, thereby preventing toner leakage from the toner cartridge.
In the image forming apparatus, since the toner cartridge is arranged in opposed relation to the developing device in the longitudinal direction of the magnet roller, the size of the image forming apparatus can be reduced in the up and down direction, as compared with a case where the toner cartridge is arranged in opposed relation to the developing device in the up and down direction that intersects a longitudinal direction of the toner cartridge.
However, in the image forming apparatus, in a state where the toner cartridge is mounted in the casing of the developing device, the replenishing port is positioned above the supply port, and a toner in the toner cartridge is accommodated at a position above the replenishing port. Therefore, the toner cartridge and the image forming apparatus increase in size in the up and down direction, so that miniaturization of the image forming apparatus in the up and down direction is limited.
Further, in the image forming apparatus, the toner cartridge is attached and detached to and from the casing of the developing device along the longitudinal direction of the magnet roller during replacement. For this reason, when the longitudinal size of the image forming apparatus body is limited, the longitudinal size of the toner cartridge needs to be reduced. In that case, there is a possibility that a sufficient amount of toner can not be accommodated in the toner cartridge.
In the image forming apparatus of a toner cartridge replaceable type, it is desirable to be able to easily replace the toner cartridge.
In the toner replenishing device, a user needs to directly operate the toner cartridge when opening/closing the shutter member. Therefore, in order to open/close the shutter member, the user should first open the cover, and then operate the toner cartridge. Further, after opening/closing the shutter member, the user need to close the cover, which is laborsome.
In the color electrophotographic printer, a user has to directly operate the toner cartridge when opening/closing the cartridge-side shutter and the developer-side shutter, which requires similar labor if the printer includes a structure equivalent to the cover described above.
In the laser printer, the shutter of the toner cartridge is opened/closed in conjunction with opening/closing of the upper structure, thereby achieving laborsaving in opening/closing of the shutter. However, there is no shutter for opening/closing the replenishing port in the developer, so that toner leakage from the developer (on the apparatus body side) is a concern during attachment/detachment of the toner cartridge.